The P. Gagnon & Son Blog

I Hear A Hissing Noise Coming From My Propane Tank

What’s that sound?

fuel tank noises maine

If you use propane at your Seacoast Region home, you should familiarize yourself with your propane tank and how it works, as well as propane safety information.

One thing that may have you worried is if you hear a hissing sound coming from your propane tank. The understandable first thought is that your propane tank is leaking and that it’s unsafe. That’s why we recommend getting in touch with us immediately if you hear a hissing sound. If there is a leak, we can safely and properly deal with it. The sound may also be from your propane tank’s safety relief valve doing its job, which may indicate problems that we need to fix.

Propane tanks of all sizes, including those used for grilling, are required by law to include pressure relief mechanisms that allow excess pressure to be released from within the tank.

About safety relief valves:

Safety relief valve with label

  • Other names for safety relief valves include pop-off valves, relief valves, or pressure venting valves.
  • The safety relief valve is kept shut by a sturdy spring as long as the pressure inside the tank is at a safe level.
  • If the pressure in the tank reaches the same amount of pressure of the spring, the safety relief valve is opened. That’s when you’ll hear a hissing sound coming from the tank. That sound is the pressure in the tank being dissipated.
  • The valve will fully open in cases where the tank pressure is significantly greater than the spring pressure. If that happens, you’ll hear a pop.
  • Once the pressure is down below the pressure of the spring, the valve should close on its own. But that does not mean that the problem is solved.
  • A pressure relief valve opening is a sign that something may be wrong with your tank.

Get in touch with us right away if your safety relief valve opens so we can inspect your tank and fix any problems that are found. DO NOT try to replace the safety relief valve or fix it or your propane tank yourself. Any work on a propane tank is not a DIY project and must be done by a trained service technician.

Why propane expands inside your propane tank

Propane, like any other liquid, expands in heat. Propane’s expansion, on the other hand, is 17 times greater than that of water.

With that kind of expansion, there needs to be room inside your propane tank to accommodate it. Therefore, your propane tank is filled to 80% rather than 100%. The propane in the tank can safely expand thanks to that 20% of empty space within it.

Expansion is also the reason for why propane tanks are painted light colors such as white or beige. These light colors reflect heat away from your tank, minimizing how much the propane in there will expand. Dark colors, on the other hand, retain heat. That much heat can cause the propane inside your tank to expand to dangerous levels.

While you may not want a white or beige propane tank in your landscaping, leave it alone.

P. Gagnon & Son is dedicated to safety in all of our propane services. Become a customer and have peace of mind.